Semiconductor device having groove-shaped via-hole

ABSTRACT

The semiconductor device has insulating films  40, 42  formed over a substrate  10 ; an interconnection  58  buried in at least a surface side of the insulating films  40, 42 ; insulating films  60, 62  formed on the insulating film  42  and including a hole-shaped via-hole  60  and a groove-shaped via-hole  66   a  having a pattern bent at a right angle; and buried conductors  70, 72   a  buried in the hole-shaped via-hole  60  and the groove-shaped via-hole  66   a . A groove-shaped via-hole  66   a  is formed to have a width which is smaller than a width of the hole-shaped via-hole  66 . Defective filling of the buried conductor and the cracking of the inter-layer insulating film can be prevented. Steps on the conductor plug can be reduced. Accordingly, defective contact with the upper interconnection layer and the problems taking place in forming films can be prevented.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 13/013,103 filed on Jan. 25, 2011, which is a divisional ofU.S. patent application Ser. No. 11/898,548 filed on Sep. 13, 2007, nowU.S. Pat. No. 7,906,851, which is a divisional of U.S. patentapplication Ser. No. 10/622,614, filed on Jul. 21, 2003, now U.S. Pat.No. 7,301,241, which is based upon and claims the benefit of priorityfrom the prior Japanese Patent Application No. 2002-223343, filed inJul. 31, 2002, the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

The present invention relates to a semiconductor device, morespecifically a semiconductor device having a conductor buried in ahole-shaped pattern or a groove-shaped pattern formed in an insulatingfilm, and a method for fabricating the semiconductor device.

As semiconductor devices are larger-scaled and higher integrated, thedesign rules of interconnections are more shrunk with generations.Conventionally, interconnection layer has been formed by depositing andpatterning the interconnection material by lithography and dry etching.However, this has found technological limitation as the generationsadvance. As a new process for forming interconnection layer, which takesthe place of the conventional interconnection layer forming process, theso-called damascene process, i.e., forming a groove-shaped pattern or ahole-shaped pattern in inter-layer insulating film and then buryinginterconnection material in the groove or the hole is being used. Thedamascene process can easily form interconnection layer of lowresistance materials, such as copper, etc., which are difficult forreactive etching, and is very effective to form interconnection layer oflow resistance having micronized pattern.

The damascene process is used not only in forming the usualinterconnection layers, but also in forming various structures. Forexample, the Laid-open Japanese Patent Application No. 2000-124403discloses an inductor and the method for fabricating the same fabricatedby the damascene process.

Then, a conventional semiconductor device fabricated by the damasceneprocess will be explained by means of a semiconductor device includingan inductor. FIGS. 35A and 35B are plan views of the conventionalsemiconductor device. FIG. 36 is a diagrammatic view of the conventionalsemiconductor device, which shows the structure thereof. FIG. 36 is thesectional view along the line A-A′ in FIG. 35B.

An etching stopper film 302 and an inter-layer insulating film 304 areformed on a substrate 300. Interconnection groove 308 is formed in theinter-layer insulating film 304 and the etching stopper film 302. Aninterconnection 314 having a diffusion preventing film 310 and a copperfilm 312 is formed in the interconnection groove 308.

An etching stopper film 316 and an inter-layer insulating film 318 areformed on the inter-layer insulating film 304 with the interconnection314 buried in. Groove-shaped via-holes 326 are formed in the inter-layerinsulating film 318 and the etching stopper film 316 down to theinterconnection 314. An etching stopper film 320 and an inter-layerinsulating film 322 are formed on the inter-layer insulating film 318.Interconnection groove 332 is formed in the inter-layer insulating film322 and the etching stopper film 320. An interconnection 338 having adiffusion preventing film 334 and a copper film 336 and connected to theinterconnection 314 is formed in the via-holes 326 and theinterconnection groove 332.

An etching stopper film 340 and an inter-layer insulating film 342 areformed on the inter-layer insulating film 322 with the interconnection338 buried in. Groove-shaped via-holes 348 are formed in the inter-layerinsulating film 342 and the etching stopper film 340 down to theinterconnection 338. An etching stopper film 344 and an inter-layerinsulating film 346 are formed on the inter-layer insulating film 342.Interconnection groove 350 is formed in the inter-layer insulating film346 and the etching stopper film 344. An interconnection 356 having adiffusion preventing film 352 and a copper film 354 and connected to theinterconnection 338 is formed in the via-holes 348 and theinterconnection groove 350.

As shown in FIG. 35A, the interconnections 314, 338, 356 are formed in aspiral in plane, forming the so-called spiral inductor. As shown in FIG.35B, the interconnections 338, 356 have via portions buried in aplurality of groove-shaped patterns (the via-holes 326, 348) formedalong extending direction of the interconnections 338, 356, and maininterconnection portions formed on the via portions. Thus, the viaportions buried in the groove-shaped patterns, and a plurality of theinterconnection layers are formed, whereby the inductor of lowinterconnection resistance can be fabricated.

As described above, the interconnections formed of mainly copper areused, and the interconnection layers are laid one on another, wherebythe inductor of low interconnection resistance can be formed. On theother hand, the copper interconnection is more corrosive than theconventionally used aluminum interconnection and is difficult for wirebonding unsuitably as an uppermost interconnection layer.

Based on these views, the inventor of the present application has madestudies of a new inductor structure that the uppermost interconnectionlayer is formed of aluminum, and an inductor is formed, including thealuminum interconnection layer. However, it has been found that theinductor including the aluminum interconnection layer has new problemswhich has not taken place in inductors formed of only copperinterconnection layers.

FIG. 37 is the sectional view along the line B-B′ in FIG. 35B. As shownin FIG. 37, when contact plugs 362 each having a barrier metal layer 358and a tungsten film 360 and buried in the via-holes 348 and, and aninterconnection 370 having a layer structure of a titanium nitride film368/an aluminum film 366/a titanium nitride film 364 and formed on theinter-layer insulating film 342 with the contact plugs 362 buried in areformed in place of the interconnection 356, defective filling of thecontact plugs 362 has often taken place at the pattern corners of thevia-holes 348 (see the parts A and B in FIG. 37).

When the groove-shaped via-holes 348 are formed adjacent to each other,cracks are often made in the inter-layer insulating film 342 at thepattern corner of the outermost via-hole 348 (see the part C in FIG.37). Also in the interconnections 338, defective filling of theinterconnections 338 has often taken place at the pattern corners of thevia-holes 326 (see the part D in FIG. 37).

The defective filling of the contact plugs causes poor coverage of thebarrier metal layer or the aluminum film in forming the upperinterconnection layer formed thereon, the transfer of steps onto thesurface of the interconnection layer formed thereon, etc. (see the partsA, B and E in FIG. 37). Defective formation of the upper interconnectionlayer causes electrically weak parts in the connections between thecontact plug and the interconnection.

Cracks in the inter-layer insulating film are a cause of inducingdiffusion of copper from the lower interconnection layer. In the caseshown in FIG. 37, the etching stopper film of the diffusion preventingfilm and the silicon nitride film prohibits the diffusion of copper intothe inter-layer insulating film. If cracks are made in the inter-layerinsulating film, however, the diffusion prohibiting effect of thediffusion preventing film and the etching stopper film is lowered.Copper, which is easily diffused into silicon oxide film at certaintemperatures, is a cause of lowering the breakdown voltage between theinterconnections when the interconnection of a different potential ispresent in its neighborhood. The copper is exposed in the interface atthe cracks, which is a cause of poor electromigration immunity whenexcessive current flows.

The defective filling of the contact plugs is true with contact plugsinterconnecting a semiconductor substrate with a first interconnectionlayer. As exemplified in FIG. 38, in a semiconductor device comprising asilicon substrate 400 having a impurity diffused layer 402 formedtherein, insulating films 404, 406, 408, 410 sequentially formed on thesilicon substrate 400, contact plugs 16 formed of a barrier metal 412and a tungsten film 414 buried in the insulating films, and aninterconnection 422 formed of a diffusion preventing film 418 and acopper film 420 buried in the insulating films 408, 410, when thecontact plugs 416 are formed in groove-shaped via-holes, the samedefective filling as that in the parts A and B takes place at thecorners of the groove-shaped via-holes.

The problems taking place in the application of the above-describedinterconnection structure has been explained by means of the inductor.However, the same problems take place in forming structures using thegroove-shaped via patterns. For example, in the case that thegroove-shaped via patterns are used in a guard ring (also called as aseal ring) for protecting the device from water from the environments,etc., the above-described defect is a cause of degrading the moistureresistance. Especially, the guard ring for a redundant circuit, whichencloses a fuse region, cracks very influentially occur inside thechips.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a semiconductor devicehaving a structure that a conductor is buried in a hole-shaped patternor a groove-shaped pattern formed in an insulating film and a method forfabricating the same, which can prevent the defective filling of theconductor and cracking of the insulating film due to the defectivefilling.

According to one aspect of the present invention, there is provided asemiconductor device comprising: a first insulating film formed over asubstrate; a first interconnection buried in at least a surface side ofthe first insulating film; a second insulating film formed on the firstinsulating film with the first interconnection buried in, and includinga groove-shaped via-hole having a pattern which is bent at a right angleformed in a region above the first interconnection; and a first buriedconductor filled in the groove-shaped via-hole.

According to another aspect of the present invention, there is provideda semiconductor device comprising: a first insulating film formed over asubstrate; a first interconnection buried in at least a surface side ofthe first insulating film, the first interconnection having a patternwhich is bent at a right angle; a second insulating film formed on thefirst insulating film with the first interconnection buried in, andincluding a groove-shaped via-hole formed in a region above the firstinterconnection; and a first buried conductor filled in thegroove-shaped via-hole, the groove-shaped via-hole being interrupted ata corner of the pattern of the first interconnection.

According to further another aspect of the present invention, there isprovided a semiconductor device comprising: a first and a secondimpurity diffused regions formed in a semiconductor substrate; a firstinsulating film formed on the semiconductor substrate, and including agroove-shaped via-hole having a pattern bent at a right angle formed ina region above the first impurity diffused region and a hole-shapedvia-hole formed in a region above the second impurity diffused region; afirst buried conductor buried in the groove-shaped via-hole; and asecond buried conductor buried in the hole-shaped via-hole, a width ofthe groove-shaped via-hole being 20-140% of a width of the hole-shapedvia-hole.

According to further another aspect of the present invention, there isprovided a method for fabricating a semiconductor device including afirst insulating film formed over a substrate, a first interconnectionburied in at least a surface side of the first insulating film, and asecond insulating film formed on the first insulating film with thefirst interconnection buried in and including a groove-shaped via-holeand a hole-shaped via-hole which are opened on the firstinterconnection, in forming the groove-shaped via-hole and thehole-shaped via-hole in the second insulating film, a mask patternhaving a design width of the groove-shaped via-hole smaller than adesign width of the hole-shaped via-hole being used to form thegroove-shaped via-hole and the hole-shaped via-hole.

According to further another aspect of the present invention, there isprovided a method for fabricating a semiconductor device including afirst insulating film formed over a substrate, a first interconnectionburied in at least the surface side of the first insulating film, asecond insulating film formed on the first insulating film with thefirst interconnection buried in and including a groove-shaped via-holeand a hole-shaped via-hole which are opened on the firstinterconnection, and a buried conductor buried in the groove-shapedvia-hole and the hole-shaped via-hole, in forming the buried conductor,a deposited film thickness of a conducting film to be the buriedconductor being set in consideration of a maximum width of thegroove-shaped via-hole, so that the groove-shaped via-hole and thehole-shaped via-hole are filled by the buried conductor.

As described above, according to the present invention, in thesemiconductor device having the structure that conductors are filled inthe hole-shaped pattern and the groove-shaped pattern formed in theinsulating films, even when a difference is generated between a finishedsize of the hole-shaped pattern and a finished size of the groove-shapedpatterns, the defective filling of the buried conductor and theinterconnections can be prevented. The defective filling of the buriedconductor is prevented, whereby the cracking of the inter-layerinsulating film can be prevented. Steps on the buried conductor plug canbe reduced, so that the step cannot be influential on the upperinterconnection layers and insulating layers. Accordingly, defectivecontact with the upper interconnection layer and the problems takingplace in forming films can be prevented, and resultantly thesemiconductor device can have high water resistance and highinterconnection reliability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a plan view of design pattern of an inductor device region.

FIG. 1B is a plan view of design pattern of an ordinary innerinterconnection region.

FIG. 2A is a plan view of the finished pattern images of the inductordevice region on a wafer.

FIG. 2B is a plan view of the finished pattern images of the ordinaryinner interconnection region on a wafer.

FIGS. 3A-3F are images of the inductor device region observed by ascanning electron microscope.

FIGS. 4A and 4B are plan views of a design structure of thesemiconductor device according to a first embodiment of the presentinvention, which show the structure thereof.

FIGS. 5 and 6 are diagrammatic sectional views of the semiconductordevice according to the first embodiment of the present invention, whichshow the structure thereof.

FIGS. 7A-7C, 8A-8C, 9A-9B, 10A-10B, 11A-11B, 12A-12B, 13A-13B, and 14are sectional views of the semiconductor device according to the firstembodiment of the present invention in the steps of the method forfabricating the same, which show the method.

FIG. 15 is a plan view of a design structure of the semiconductor deviceaccording to a second embodiment of the present invention, which showsthe structure thereof.

FIG. 16 is a plan view of a design structure of the semiconductor deviceaccording to a modification of the second embodiment of the presentinvention, which shows the structure thereof.

FIG. 17 is a plan view of a design structure of the semiconductor deviceaccording to a third embodiment of the present invention, which showsthe structure thereof.

FIG. 18 is a plan view of a design structure of the semiconductor deviceaccording to a fourth embodiment of the present invention, which showsthe structure thereof.

FIG. 19 is a plan view of the semiconductor device according to a fifthembodiment of the present invention, which shows the structure thereof.

FIG. 20 is a plan view of the semiconductor device according to amodification of the fifth embodiment of the present invention, whichshows the structure thereof.

FIG. 21 is a plan view of the semiconductor device according to a sixthembodiment of the present invention, which shows the structure thereof.

FIGS. 22 and 23 are plan views of the semiconductor devices according tomodifications of the sixth embodiment of the present invention, whichshow the structure thereof.

FIG. 24 is a plan view of the semiconductor device according to aseventh embodiment of the present invention, which shows the structurethereof.

FIG. 25 is a plan view of the semiconductor device according to amodification of the seventh embodiment of the present invention, whichshows the structure thereof.

FIG. 26 is a diagrammatic sectional view of the semiconductor deviceaccording to an eighth embodiment of the present invention, which showsthe structure thereof.

FIGS. 27A-27B and 28A-28B are sectional views of the semiconductordevice according to the eighth embodiment of the present invention inthe steps of the method for fabricating the same, which show the method.

FIGS. 29A-29C are views explaining causes of the generation of thedefective filling of the contact plug.

FIGS. 30A-30C are views explaining means for preventing the defectivefilling of the contact plug in the fabrication steps.

FIG. 31 is a diagrammatic sectional view of the semiconductor deviceaccording to a ninth embodiment of the present invention, which showsthe structure thereof.

FIG. 32 is a diagrammatic sectional view of the semiconductor deviceaccording to another example of the ninth embodiment of the presentinvention, which shows the structure thereof.

FIGS. 33A and 33B are plan views of the semiconductor device accordingto a first modified embodiment of the present invention, which show thestructure thereof.

FIGS. 34A and 34B are plan views of the semiconductor device accordingto a second modified embodiment of the present invention, which show thestructure thereof.

FIGS. 35A and 35B are plan views of the conventional semiconductordevice having the inductor, which show the structure thereof.

FIG. 36 is a diagrammatic sectional view of the conventionalsemiconductor device having the inductor, which shows the structurethereof.

FIG. 37 is a diagrammatic sectional view showing a new structureaccording to an idea of the inventor of the present application, andproblems thereof.

FIG. 38 is a diagrammatic sectional view showing the problems of theconventional semiconductor device.

DETAILED DESCRIPTION OF THE INVENTION

[Principle of the Invention]

The inventor of the present application has made earnest studies ofcauses of the defective filling of the buried conductor and the crackingof the inter-layer insulating film to successfully make it clear thatthese defects are due to a difference between a pattern size at thecorner of the groove-shaped via pattern and a pattern size of thehole-shaped via pattern. The cause of the defective filling of thecontact plug and the cracking of the inter-layer insulating film will bespecifically explained.

Usually, structures using groove-shaped vias, such as inductors, guardrings, etc., are formed simultaneously with the interconnections insidethe chips. At this time, the groove-shaped via patterns are formedsimultaneously with hole-shaped patterns, as of contact holes,via-holes, etc.

FIGS. 1A and 1B show plan views of a design pattern of an inductordevice region and an ordinary inner interconnection region. FIG. 1A is apartial plan view of the inductor device. FIG. 1B is a partial plan viewof the inner interconnection region.

FIGS. 1A and 1B show patterns of base interconnection layers andpatterns of contact plugs formed on the interconnection layers. In theinductor device region shown in FIG. 1A, 4, for example, groove-shapedvia patterns 12 are formed along the extending direction of aninterconnection 10. In the inner interconnection region shown in FIG.1B, rectangular via-holes 16 are formed down to interconnections 14.Generally, it is often that groove-shaped via patterns used in a guardring, an inductors, etc. are designed to have a width or a diameterequal to that of patterns of an inner circuit pattern. In the designshown in FIGS. 1A and 1B as well, the width of the groove-shaped viapatterns and the width (diameter) of the via-holes are designed to bethe same.

However, suitable exposure conditions required to form design patternsizes are different between the hole-shaped via pattern and thegroove-shaped via pattern. In concurrently forming the hole-shaped viapatterns and the groove-shaped via patterns, even when a width of thehole-shaped via patterns and a width of the groove-shaped via patternsare made equal to each other in design data, the finished sizes aredifferent from each other.

When the groove-shaped via patterns are exposed with an exposurecondition suitable to form the hole-shaped via patterns as designed, theexposure amount is higher than a suitable exposure amount for thegroove-shaped via pattern. The groove-shaped via pattern is wider than adesign value. Furthermore, exposure light advances in two directionstoward the corner of the groove-shaped via pattern, which widens thegroove-shaped via patterns by a higher degree there.

FIGS. 2A and 2B are plan views of the images of the finished patternsformed on a wafer, based on the design date shown in FIGS. 1A and 1B, inconsideration of the above-described pattern size shift. FIG. 2A is apartial plan view of the patterns in the inductor device region, andFIG. 2B is a partial plan view of the patterns in the innerinterconnection region. As shown, even in using the rectangular patternsas shown in FIGS. 1A and 1B, the corners of the finished patterns arealittle rounded by the proximity effect. Besides, a finished size variesdepending on a shape of the patterns. For example, when a design size ofthe diameter of the via-holes 16 was 0.50 μm, and a design size of thegroove-shaped via pattern 12 was 0.50 μm, the finished diameter of thevia-holes 16 on a wafer was 0.50 μm, and the finished width of thegroove-shaped via patterns on the wafer was 0.55 μm. At this time, adesign size of the corners of the groove-shaped via patterns was 0.71 μm(0.50 μm×√2), but the finished size was 0.80 μm.

FIGS. 3A-3F are images of the inductor device region on an actual wafer,which were observed by a scanning electron microscope. As shown in FIGS.3A and 3B, the defective filling has not taken place in the parts wherethe groove-shaped via patterns are linearly extended and the parts wherethe groove-shaped via patterns are bent at 135°. However, in the partswhere the groove-shaped via patterns are bent by 90°, as shown in FIGS.3C and 3D, the defective filling of the groove-shaped via patterns hastaken place. As shown in FIGS. 3E and 3F, cracks have been made in theouter side of the corner of the outermost groove-shaped via pattern.

Considering the above-described phenomena, the defective filling of thegroove-shaped vias will be due to the above-described pattern sizeshift. That is, when conditions for forming the contact plugs areoptimized in accordance with the via-holes 16, the filling of thecontact plugs will be insufficient at the corners of the groove-shapedvia patterns.

As for causes of the cracking of the inter-layer insulating film, theinventor's studies have been able to confirm the following phenomena. 1)The place where the cracks are made is the outer side of the corner ofthe outermost groove-shaped via pattern. 2) When the groove-shaped viasare sufficiently filled, no cracks are made in the inter-layerinsulating film. 3) When the base is not a copper interconnection (but,e.g., an aluminum interconnection), no cracks are made in theinter-layer insulating film even when the defective filling has takenplace in the groove-shaped vias. Considering these points, the crackingof the inter-layer insulating film will be due to the thermal expansioncoefficient difference between the lower copper interconnection and theupper tungsten plugs. The thermal expansion coefficient differencebetween the two generates a tensile stress toward the inside of thepattern corner, and a void formed by the defective filling acceleratesshrinkage of the tungsten plugs, whereby cracks are made in theinter-layer insulating film at the pattern corner.

Accordingly, in order to prevent cracking of the inter-layer insulatingfilm, some countermeasures for the defective filling of thegroove-shaped vias may be taken. To prevent the defective filling of thegroove-shaped vias it is considered 1) to contrive the patterns and 2)to optimize the process.

As described above, a main cause of the defective filling of thegroove-shaped vias will be the size shift of the groove-shaped viapatterns. Accordingly, for the above-described countermeasure 1),contrivances that design pattern sizes are set in consideration of adifference of finished sizes of the hole-shaped via pattern and thegroove-shaped via pattern; a bend angle of the groove-shaped via patternis made large; a width of the groove-shaped via pattern is made smallerselectively at the corner thereof; the groove-shaped via patterns haveno corners; etc. are considered. From the viewpoint that only thecracking of the inter-layer insulating film is prevented, theabove-described contrivances may be applied to at least the outermostgroove-shaped via pattern. As for the above-described countermeasure 2),it is considered to make a film thickness of the tungsten film formingthe contact plugs to be buried in to thereby completely fill thegroove-shaped via pattern.

The above-described contrivances for the pattern may be applied to thepattern of the copper interconnection below the groove-shaped vias. Itis true with the damascene interconnection that the defective fillingtends to occur at the corner of the groove-shaped vias.

A First Embodiment

The semiconductor device and the method for fabricating the sameaccording to a first embodiment of the present invention will beexplained with reference to FIGS. 4A-4B, 5, 6, 7A-7C, 8A-8C, 9A-9B,10A-10B, 11A-11B, 12A-12B, 13A-13B, and 14.

FIGS. 4A and 4B are plan views of a design structure of thesemiconductor device according to the present embodiment. FIGS. 5 and 6are diagrammatic sectional views of the semiconductor device accordingto the present embodiment, which show the structure. FIGS. 7A to 14 aresectional views of the semiconductor device according to the presentembodiment in the steps of the method for fabricating the same, whichshow the method.

First, the structure of the semiconductor device according to thepresent embodiment will be explained with reference to FIGS. 4A to 6.FIG. 4A is a partial plan view of a design structure of the innercircuit region of the semiconductor device according to the presentembodiment. FIG. 4B is a partial plan view of a design structure of thegroove-shaped via pattern forming region of the semiconductor deviceaccording to the present embodiment. FIG. 5 is a diagrammatic sectionalview of the semiconductor device along the line A-A′ in FIG. 4A. FIG. 6is a diagrammatic sectional view of the semiconductor device along theline B-B′ in FIG. 4B.

The semiconductor device according to the present embodiment includesthe inner circuit region and the groove-shaped via pattern formingregion. Here, the inner circuit region means the ordinary device regionincluding a structure of an upper and a lower interconnection layersinterconnected to each other through via-holes (hole-shaped vias). Thegrooved via pattern region means a region where a structure usinggroove-shaped via-holes is formed, and is, e.g., an inductor deviceregion and a guard ring region around a fuse circuit, a chip or others.FIG. 4B is a view of the enlarged corner of the groove-shaped viapattern, and the groove-shaped via pattern is formed, extended upwardand left as viewed in the drawing.

An etching stopper film 22 and an inter-layer insulating film 24 areformed on a substrate 20. In the specification of the presentapplication, the substrate 20 can be a semiconductor substrate itself,and can also include a semiconductor substrate with semiconductorelements, such as transistors, etc., formed on and such substrate withone or more interconnection layers further formed on.

Interconnection grooves 28 are formed in the inter-layer insulating film24 and the etching stopper film 22. Interconnections 34 each including adiffusion preventing film 30 a and a copper film 32 are formed in theinterconnection grooves 28.

An etching stopper film 36 and an inter-layer insulating film 38 areformed on the inter-layer insulating film 24 with the interconnections34 buried in. As shown in FIG. 4A and FIG. 5, a via-hole 46 is formed inthe inter-layer insulating film 38 and the etching stopper film 36 inthe inner circuit region down to the interconnection 34. In theinter-layer insulating film 38 and the etching stopper film 36 in thegroove-shaped via pattern forming region, as shown in FIG. 4B and FIG.6, a groove-shaped via-hole 46 a is formed. An etching stopper film 40and an inter-layer insulating film 42 are formed on the inter-layerinsulating film 38. Interconnection grooves 52 are formed in theinter-layer insulating film 42 and the etching stopper film 40.Interconnections 58 each including a diffusion preventing film 54 a anda copper film 56 are formed in the via-holes 46, 46 a and theinterconnection groove 52, electrically connected to the interconnection34.

An etching stopper film 60 and an inter-layer insulating film 62 areformed on the inter-layer insulating film 42 with the interconnections58 buried in. As shown in FIG. 4A and FIG. 5, via-holes 66 are formeddown to the interconnection 58 in the inter-layer insulating film 62 andthe etching stopper film 60 in the inner circuit region. In theinter-layer insulating film 62 and the etching stopper film 60 in thegroove-shaped via pattern forming region, as shown in FIG. 4B and FIG.6, a groove-shaped via-hole 66 a is formed. Contact plugs 72 eachincluding a barrier metal layer 68 a and a tungsten film 70 are formedin the via-holes 66. A groove-shaped contact plug 72 a including thebarrier metal layer 68 a and the tungsten film 70 is formed in thevia-hole 66 a.

Interconnections 82 of a layer structure of a titanium nitride film78/an aluminum film 76/a titanium nitride film 74 are formed on theinter-layer insulating film 62 with the contact plugs 72, 72 a buriedin. A cover film including a silicon oxide film 84 and a silicon nitridefilm 86 is formed on the inter-layer insulating film 62 with theinterconnections 82 formed on.

The semiconductor device according to the present embodiment ischaracterized mainly in that the diameter of the hole-shaped via-holes66 and the width of the groove-shaped via-hole 66 a are different fromeach other in the design pattern size. That is, in FIG. 4B, thegroove-shaped via-hole 66 a having the width which is equal to thediameter of the via-holes 66 is drawn in the dotted line. The outer edgeof the design pattern of the via-hole 66 a is positioned inner of thedotted line.

For example, when a diameter of the via-holes 66 is designed to be 0.5μm, a width of the via-hole 66 a is designed to be 0.4 μm. Even whenexposure with a suitable exposure condition for forming the via-holes 66in the design size overexposes for forming the via-hole 66 a, a finishedwidth of the via-hole 66 a can be substantially equal to a finisheddiameter of the via-holes 66. Accordingly, when the via-holes 66 arefilled with the contact plugs 72, the via-hole 66 a can be also filledwith the contact plug 72 a.

A shift amount of the pattern size between the hole-shaped patterns andthe groove-shaped pattern on a wafer varies corresponding tocharacteristics, etc. of the aligner, the etching system, etc.Accordingly, how much a width of the via-hole 66 a is decreased withrespect to a diameter of the via-holes 66 is preferably set suitablycorresponding to a shift amount of the pattern size between thehole-shaped patterns and the groove-shaped pattern on a wafer.

It is important that a finished width of the via-hole 66 a is set sothat when the contact plugs 72 are buried in the via-holes 66, thecontact plug 72 a is completely filled in the via-hole 66 a. Thus, thefinished width of the via-hole 66 a is not essentially equal to thefinished diameter of the via-holes 66. As long as the via-hole 66 a hasa width which permits the contact plug 72 a to be completely filled inthe via-hole 66 a, a diameter of the via-holes 66 can be larger orsmaller than a finished width of the via-hole 66 a.

The device of the generations the inventor of the present invention hasmade studies of uses a 0.5 μm hole-shaped via diameter. In this case,the defective filling did not take place in the groove-shaped via whosewidth was not more than about 140% of the hole-shaped via diameter,i.e., about 0.7 μm. On the other hand, a minimum width required by thegroove-shaped via cannot be generally said because the minimum widthdepends on a resolution of the aligner and a thickness of the barriermetal layer, but the groove-shaped via having a width of not less thanabout 20% of a diameter of the hole-shaped vias will not hinder theformation of the contact plug. When conditions for forming the contactplug is optimized based on a hole-shaped via diameter, it is reasonableto design a width of the groove-shaped via to be smaller than a width ofthe hole-shaped vias.

When the defective filling of the via-hole 46 a takes place in theprocess of forming the interconnections 58, a width of the via-hole 46 amay be suitably designed as described above.

Generally, when the hole-shaped patterns and the groove-shaped patternare concurrently formed, the groove-shaped pattern is substantiallyoverexposed. Accordingly, a finished width of the groove-shaped patternis substantially equal to a finished width of the hole-shaped patterns,or a finished width of the groove-shaped pattern is smaller than afinished width of the hole-shaped patterns, a design size of thegroove-shaped pattern will be made smaller than a design size of thehole-shaped patterns.

Next, the method for fabricating the semiconductor device according tothe present embodiment will be explained with reference to FIGS. 7A to14. The inner circuit region and the groove-shaped via pattern formingregion are different from each other in plane layout but are notdifferent from each other in the fabrication steps. The method forfabricating the semiconductor device according to the present embodimentwill be explained below with reference to the sectional views of theinner circuit region.

First, an etching stopper film 22 of a 50 nm-thick silicon nitride filmand an inter-layer insulating film 24 of a 500 nm-thick silicon oxidefilm are sequentially formed on a substrate 20 by, e.g., CVD.

Next, a photoresist film 26 exposing regions for forminginterconnections is formed on the inter-layer insulating film 24 byphotolithography (FIG. 7A).

Then, under etching conditions which provide a sufficient selectiveratio with respect to the silicon nitride film, and with the photoresistfilm 26 as a mask and with the etching stopper film 22 as a stopper, theinter-layer insulating film 24 is anisotropically etched to form theinterconnection grooves 28 in the inter-layer insulating film 24.

Then, the photoresist film 26 is removed by asking using, e.g., oxygenplasma.

Then, under etching conditions which provide a sufficient selectiveratio with respect to the silicon oxide film, and with the inter-layerinsulating film 24 with the interconnection grooves 28 formed in as amask, the etching stopper film 22 is anisotropically etched to open theinterconnection grooves 28 down onto the substrate 20 (FIG. 7B).

The etching stopper film is etched after the photoresist film 26 hasbeen removed so as to prevent the substrate 20 from being damaged byashing for removing the photoresist film 26. In a case where any layersto be damaged by ashing (e.g., a copper interconnection or others) arenot formed on the top of the substrate 20, the inter-layer insulatingfilm 24 and the etching stopper film 22 may be continuously etched withthe photoresist film 26 as a mask.

Then, a 50 nm-thick tantalum film 30 and a 1500 nm-thick copper film 32are deposited on the entire surface by, e.g., sputtering (FIG. 7C). Itis possible that the tantalum film 30, and a thin copper film (notshown) as a seed layer are deposited by sputtering, and the copper film32 is formed by plating with the copper film as a seed.

Then, the copper film 32 and the tantalum film 30 are planarly removedby, e.g., chemical mechanical polishing (CMP) until the inter-layerinsulating film 24 is exposed. The interconnections 34 filled in theinterconnection grooves 28 and including the diffusion preventing film30 a for preventing the diffusion of copper and formed of the tantalumfilm 30, and the copper film 32 forming the major part of theinterconnections 34 are thus formed (FIG. 8A).

Then, the etching stopper film 36 of a 50 nm-thick silicon nitride film,the inter-layer insulating film 38 of a 750 nm-thick silicon oxide film,the etching stopper film 40 of a 50 nm-thick silicon nitride film, andthe inter-layer insulating film 42 of a 500 nm-thick silicon oxide filmare sequentially formed by, e.g., CVD on the inter-layer insulating film24 with the interconnections 34 buried in. The etching stopper film 36functions also as a diffusion preventing film for preventing thediffusion of the copper from the interconnections 34.

In a case where steps are formed due to dishing, etc. in the step offorming the interconnections 34, it is possible that the inter-layerinsulating film 38 is deposited in a thickness larger than a prescribedthickness and polished planarly to the prescribed thickness by CMP, andthen the etching stopper film 40 is deposited.

Then, a photoresist film 44 exposing the regions where the via-holes 46,46 a are to be formed in the inter-layer insulating film 38 is formed onthe inter-layer insulating film 42 by photolithography (FIG. 8B).

Next, with the photoresist film 44 as a mask and with the etchingstopper film 36 as a stopper, the inter-layer insulating film 42, theetching stopper film 40 and the inter-layer insulating film 38 aresequentially anisotropically etched with etching conditions changed toform the via-holes 46 in the inter-layer insulating film 38 in the innercircuit region and the via-hole 46 a in the inter-layer insulating filmin the groove-shaped via pattern forming region.

In a case where the defective filling takes place in the interconnection58, which will be formed later, it is possible that a photomask isdesigned so that a design diameter of the via-holes 46 and a designwidth of the via-hole 46 a are different from each other, and thephotoresist film 44 is formed by using the photomask. When a designdiameter of the via-holes 46 is, e.g., 0.5 μm, a design width of thevia-hole 46 a is set to be, e.g., 0.4 μm, whereby the finished diameterof the via-holes 46 can be substantially equal to the finished width ofthe via-hole 46 a, and the defective filling of the interconnection 58can be precluded.

Then, the photoresist film 44 is removed by asking using, e.g., oxygenplasma (FIG. 8C).

Next, a non-photosensitive resin 48 is applied by, e.g., spin coating,and then the non-photosensitive resin 48 on the inter-layer insulatingfilm 42 is dissolved and removed while the non-photosensitive resin 48in the via-holes 46 is left.

Then, a photoresist film 50 exposing a region where the interconnectionto be formed in the inter-layer insulating film 42 is formed on theinter-layer insulating film 42 by photolithography (FIG. 9A). Thephotoresist film 50 is selected out of materials which do not mix withthe non-photosensitive resin 40 and a developer of which does not solvethe non-photosensitive resin 40.

Under etching conditions which can provide a sufficient selective ratiowith respect to the silicon nitride film, with the photoresist film 50as a mask and with the etching stopper film 40 as a stopper, theinter-layer insulating film 42 is anisotropically etched to form theinterconnection grooves 52 in the inter-layer insulating film 42.

Then, the photoresist film 42 and the non-photosensitive resin 40 areremoved by asking using, e.g., oxygen plasma (FIG. 9B).

Next, the etching stopper films 36, 40 are anisotropically etched underetching conditions which can provide a sufficient selective ratio withrespective to the silicon oxide film and with the inter-layer insulatingfilm 42 with the interconnection grooves 52 formed in and theinter-layer insulating film 38 with the via-holes 46 formed in as masksto open the interconnection grooves 52 down onto the inter-layerinsulating film 38 and to open the via-holes 46 down onto theinterconnection 34 (FIG. 10A).

Then, a 50 nm-thick tantalum film 54 and a 1500 nm-thick copper film 56are deposited on the entire surface by, e.g., sputtering. It is possiblethat the tantalum film 54, and a thin copper film (not shown) as a seedlayer are deposited by sputtering, and then with the copper film as aseed, the copper film 56 of a prescribed thickness is formed by plating.

Next, the copper film 56 and the tantalum film 54 are planarly removedby, e.g., CMP until the inter-layer insulating film 42 is exposed. Thus,the interconnections 58 which is filled in the interconnection grooves52 and the via-holes 46 and includes the diffusion preventing film 54 aformed of the tantalum film 54 for preventing the diffusion of thecopper, and the copper film 56 which forms the major part of theinterconnection are thus formed (FIG. 11A).

Then, the etching stopper film 60 of a 50 nm-thick silicon nitride film,and the inter-layer insulating film 62 of a 750 nm-thick silicon oxidefilm are sequentially deposited by, e.g., CVD on the inter-layerinsulating film 42 with the interconnections 58 buried in. The etchingstopper film 60 functions also as the diffusion preventing film forpreventing the diffusion of the copper from the interconnection 58.

In a case where steps are formed due to dishing, etc. in the step offorming the interconnection 58, it is possible that the inter-layerinsulating film 62 is deposited in a thickness larger than a prescribedthickness and polished planarly to the prescribed thickness by CMP.

Then, a photoresist film 64 exposing regions where the via-holes 66, 66a are to be formed in the inter-layer insulating film 62 is formed onthe inter-layer insulating film 62 by photolithography (FIG. 11B). Asshown in FIG. 4, the photomask is designed so that a design diameter ofthe via-holes 66 and a design width of the via-hole 66 a are differentfrom each other, and the photoresist film 64 is formed by using thephotomask.

Next, the inter-layer insulating film 62 is anisotropically etched withthe photoresist film 64 as a mask and with the etching stopper film 60as a stopper to form the via-holes 66 in the inter-layer insulating film62 in the inner circuit region and the via-hole 66 a in the inter-layerinsulating film 62 in the groove-shaped via pattern forming region. Whenthe design diameter of the via-holes 66 is, e.g., 0.5 μm, and the designwidth of the via-hole 66 a is, e.g., 0.4 μm, the finished diameter ofthe via-holes 66 and the finished width of the via-hole 66 a are bothabout 0.5 μm.

Then, the photoresist film 64 is removed by asking using, oxygen plasma.

Next, under etching conditions which can provide a sufficient selectiveratio with respect to the silicon oxide film and with the inter-layerinsulating film 62 with the via-holes 66 formed in as a mask, theetching stopper film 60 is anisotropically etched to open the via-holes66, 66 a down onto the interconnection 58 (FIG. 12A).

Then, a 50-nm-thick titanium nitride film and a 300 nm-thick tungstenfilm 70 are sequentially formed respectively by, e.g., sputtering andCVD (FIG. 12B).

Next, the tungsten film 70 and the titanium nitride film 68 are planarlyremoved by, e.g., CMP until the inter-layer insulating film 62 isexposed. The contact plugs 72 filled in the via-holes 66 and includingthe barrier metal layer 68 a formed of the titanium nitride film 68 andthe tungsten film 70, and the contact plugs 72 a filled in the via-hole66 a and including the barrier metal layer 68 a formed of the titaniumnitride film 68 and the tungsten film 70 are thus formed (FIG. 13A).

At this time, the finished diameter of the via-holes 66 and the finishedwidth of the via-hole 66 a are substantially equal to each other. Thecontact plugs 72 are formed under conditions for completely filling thevia-holes 66, whereby the defective filling of the contact plug 72 a canbe prevented. In a case that the groove-shaped contact plugs aredisposed adjacent to each other, the effect of preventing the crackingof the inter-layer insulating film 62 is provided.

Next, on the inter-layer insulating film 70 with the contact plugs 72,72 a buried in, a 50 nm-thick titanium nitride film 74, a 1000 nm-thickaluminum (or copper added aluminum) film 76 and a 50 nm-thick titaniumnitride film 78 are sequentially deposited by, e.g., sputtering.

Then, the photoresist film 80 having a pattern for the interconnectionto be formed is formed on the titanium nitride film 78 byphotolithography (FIG. 13B).

Next, with the photoresist film 80 as a mask, the titanium nitride film78, the aluminum film 76 and the titanium nitride film 74 areanisotropically etched to form the interconnections 82 connected to theinterconnections 58 via the contact plugs 72 and having the layerstructure of the titanium nitride film 78/the aluminum film 76/thetitanium nitride film 74.

Then, the photoresist film 80 is removed by asking using, e.g., oxygenplasma.

Next, a 700 nm-thick silicon oxide film 84 and a 500 nm-thick siliconnitride film 86 are sequentially deposited by, e.g., CVD to form thecover film of the layer structure of the silicon nitride film 86/thesilicon oxide film 86.

Thus, the semiconductor device shown in FIGS. 4A to 6 can be fabricated.

As described above, according to the present embodiment, a pattern isdesigned so that a design width of the groove-shaped via-hole is smallerthan a design diameter of the hole-shaped via-hole, whereby even when asize difference takes place between the finished sizes of thehole-shaped pattern and the groove-shaped pattern, the defective fillingof the contact plug and the interconnection can be prevented.

The defective filling of the contact plug can be prevented, wherebyresultantly the cracking of the inter-layer insulating film can beprevented. Steps on the contact plug can be reduced, so that the stepcannot be influential on the upper interconnection layers and insulatinglayers. Accordingly, defective contact with the upper interconnectionlayer and the problems taking place in laying the films can be hindered.

In the above-described embodiment, a width of the groove-shaped via-holeis generally decreased, but only a pattern width near the corner of thegroove-shaped via-hole, where the defective filling occurs, may beselectively decreased.

A Second Embodiment

The semiconductor device and the method for fabricating the sameaccording to a second embodiment of the present invention will beexplained with reference to FIGS. 15 and 16. The same members of thepresent embodiment as those of the semiconductor device and the methodfor fabricating the same according to the first embodiment arerepresented by the same reference numbers not to repeat or to simplifytheir explanation.

FIG. 15 is a plan view of a design structure of the semiconductor deviceaccording to the present embodiment. FIG. 16 is a plan view of a designstructure of the semiconductor device according to a modification of thepresent embodiment.

The semiconductor device and the method for fabricating the sameaccording to the present embodiment is the same as the semiconductordevice and the method for fabricating the same according to the firstembodiment except that a plane design of a groove-shaped via-hole in agroove-shaped via pattern forming region is different from that of thefirst embodiment.

In the semiconductor device according to the present embodiment, asshown in FIG. 15, the pattern of the groove-shaped via-hole 66 a has thecorner bent twice each time at 135°, whereby the corner is bent totallyat 90°. The pattern of the via-hole 66 a is thus designed, whereby amaximum width of the via-hole 66 a can be made smaller in comparisonwith a maximum width the via-hole 66 a is bent once by 90°. Thus, thegeneration of the defective filling of the contact plug 72 a at thecorner can be suppressed.

In using the pattern of the present embodiment, when two corners are tooclose to each other, the proximity effect of the exposure brings aboutthe same result that is brought about when the via-hole 66 a is bent by90°. Accordingly, it is necessary to arrange two corners spaced fromeach other by some micrometers. The proximity effect varies depending ona pattern size and exposure conditions. It is preferable that a distancebetween the two corners is set in consideration of these points.

The pattern layout shown in FIG. 15 may be applied to the via-hole 46 a.The application can suppress the defective filling of theinterconnection 58.

As described above, according to the present embodiment, angle by whichthe groove-shaped via-hole is bent can be small, whereby even when adifference is generated between a finished size of the hole-shapedpattern and that of the groove-shaped patter, the defective filling ofthe contact plug and the interconnection can be precluded.

The defective filling of the contact plug is prevented, and as a result,the cracking of the inter-layer insulating film can be prevented. Stepson the contact plug can be reduced, so that the step cannot beinfluential on the upper interconnection layers and insulating layers.Accordingly, defective contact with the interconnection layer formedabove, and the problems taking place in laying the films can behindered.

In the above-described embodiment, only the patter of the via-hole 66 ais bent twice, but as shown in FIG. 16, the pattern of theinterconnection 58 as well may be bent twice.

In the above-described embodiment, the pattern of the via-hole is benttwice. However, the pattern of the via-hole may be bent three or moretimes. In the semiconductor device according to the present embodiment,an angle by which the corner is bent once is made small, whereby a sizedifference between a width of the straight portions and a width of thebent portion are made small, whereby the defective filling is reduced.As long as a pattern can attain this object, an angle and times ofbending can be any. The via pattern may be drawn in a curve of acurvature.

In the above-described embodiment, a design diameter of the hole-shapedvia-hole and a design width of the groove-shaped via-hole aresubstantially equal to each other. In the same way as in thesemiconductor device according to the first embodiment, a pattern may bedesigned so that a design diameter of the hole-shaped via-hole issmaller than a design width of the groove-shaped via-hole. Thus, thegeneration of the defective filling of the contact plug can furthersuppressed.

A Third Embodiment

The semiconductor device and the method for fabricating the sameaccording to a third embodiment of the present invention will beexplained with reference to FIG. 17. The same members of the presentembodiment as those of the semiconductor device and the method forfabricating the same according to the first and the second embodimentsshown in FIGS. 4A-16 are represented by the same reference numbers notto repeat or to simplify their explanation.

FIG. 17 is a plan view of the design structure of the semiconductordevice according to the present embodiment.

The semiconductor device and the method for fabricating the sameaccording to the present embodiment is the same as the semiconductordevice and the method for fabricating the same according to the firstand the second embodiments except that the plane design of agroove-shaped via-hole in a groove-shaped via pattern forming region isdifferent from that of the latter.

In the semiconductor device according to the present embodiment, asshown in FIG. 17, the corner of the pattern of a via-hole 66 a isremoved to form the via-hole 66 a of the straight patterns alone. Thatis, as viewed from the side of an interconnection 58, the pattern of thevia-hole 66 a is interrupted at the corner of the interconnection 58. Inusing a contact plug 72 a filled in the via-hole 66 a as a circuitdevice, such as an inductor, the removal of the corner of the pattern isa cause for increase of the interconnection resistance. However, nodesign demerit is caused by the removal of the pattern corner, when aresistance change due to the pattern change is sufficiently small.

The pattern of the via-hole 66 a is thus designed, whereby a maximumwidth of the finished via-hole 66 a can be small. Thus, the generationof the defective filling of the contact plug 72 a can be suppressed.

The layout shown in FIG. 17 is applicable to a via-hole 46 a. Thus thegeneration of the defective filling of the interconnection 58 can besuppressed.

As described above, according to the present embodiment, the corner ofthe groove-shaped pattern forming a via-hole is removed, whereby evenwhen a difference is generated between a finished via-hole size of thehole-shaped patterns and a finished via-hole size of the groove-shapedpattern, the defective filling of the contact plug and theinterconnection can be suppressed.

The defective filling of the contact plug is prevented, and resultantly,the cracking of the inter-layer insulating film can be prevented. Stepson the contact plug can be reduced, so that the step cannot beinfluential on the upper interconnection layers and insulating layers.Accordingly, defective contact with the interconnection layer formedabove, and the problems taking place in laying the films can behindered.

In the present embodiment, a design diameter of the hole-shaped via-holeand a design width of the groove-shaped via-hole are made substantiallyequal to each other. However, in the same way as in the semiconductordevice according to the first embodiment, a pattern may be designed sothat a design diameter of the hole-shaped via-hole is smaller than adesign width of the groove-shaped via-hole. Thus, the generation of thedefective filling of the contact plug can further suppressed.

A Fourth Embodiment

The semiconductor device and the method for fabricating the sameaccording to a fourth embodiment of the present invention will beexplained with reference to FIG. 18. The same members of the presentembodiment as those of the semiconductor device and the method forfabricating the same according to the first to the third embodimentsshown in FIGS. 4A to 17 are represented by the same reference numbersnot to repeat or to simplify their explanation.

FIG. 18 is a plan view of the semiconductor device according to thepresent embodiment, which shows the structure thereof.

The semiconductor device and the method for fabricating the sameaccording to the present embodiment is the same as the semiconductordevice and the method for fabricating the same according to the first tothe third embodiments except that the plane design of a groove-shapedvia-hole in a groove-shaped via pattern forming region is different fromthat of the latter.

In the semiconductor device according to the present embodiment, asshown in FIG. 18, the pattern of the via-hole 66 a is designed so thatthe exposure amount is restricted at the corner of the pattern. In thedesign shown in FIG. 18, the corner of the pattern of the via-hole 66 ais cut off. The pattern of the via-hole 66 a is thus designed, wherebyincrease of a width at the corner of the via-hole 66 a can besuppressed. Accordingly, the generation of the defective filling of acontact plug 72 a at the corner can be suppressed.

The layout of the via-hole shown in FIG. 18 may be applied to thevia-hole 46 a, whereby the generation of the defective filling of theinterconnection 58 can be suppressed.

As described above, according to the present embodiment, the pattern ofthe corner is designed so that the exposure amount at the corner isrestricted, whereby even when a difference is generated in the finishedsize between the hole-shaped pattern and the groove-shaped pattern, thegeneration of the defective filling of the contact plug and theinterconnection can be suppressed.

The defective filling of the contact plug is prevented, and resultantly,the cracking of the inter-layer insulating film can be prevented. Stepson the contact plug can be reduced, so that the step cannot beinfluential on the upper interconnection layers and insulating layers.Accordingly, defective contact with the interconnection layer formedabove, and the problems taking place in laying the films can behindered.

In the present embodiment, the groove-shaped pattern is designed to havethe corner cut off. However, as long as the exposure amount of thecorner can be restricted, the groove-shaped pattern is not limited tothe pattern shown in FIG. 18.

In the present embodiment, a design diameter of the hole-shaped via-holeand a design width of the groove-shaped via-hole are substantially equalto each other. However, in the same way as in the semiconductor deviceaccording to the first embodiment, a pattern may be designed so that adesign diameter of the hole-shaped via-hole is smaller than a designwidth of the groove-shaped via-hole. Thus, the generation of thedefective filling of the contact plug can be further suppressed.

A Fifth Embodiment

The semiconductor device and the method for fabricating the sameaccording to a fifth embodiment of the present invention will beexplained with reference to FIGS. 19 and 20. The same members of thepresent embodiment as those of the semiconductor device and the methodfor fabricating the same according to the first to the fourthembodiments shown in FIGS. 4A to 18 are represented by the samereference numbers not to repeat or to simplify their explanation.

FIG. 19 is a plan view of the semiconductor device according to thepresent embodiment, which shows the structure thereof. FIG. 20 is a planview of the semiconductor device according to one modification of thepresent embodiment, which shows the structure thereof.

The semiconductor device and the method for fabricating the sameaccording to the present embodiment is the same as the semiconductordevice and the method for fabricating the same according to the first tothe fourth embodiments except that a plane design of a groove-shapedvia-hole in a groove-shaped via pattern forming region is different fromthat of the latter.

In the semiconductor device according to the present embodiment, asshown in FIG. 19, sub-patterns 88, 90 are arranged along the outerboundary of the groove-shaped via pattern. The sub-pattern 88 is aninterconnection pattern formed of the same layer as the interconnection58, and the sub-pattern 90 is a groove-shaped via pattern formedsimultaneously with the formation of the pattern of the via-hole 66 a.

In the case that the groove-shaped contact plugs are disposed adjacentto each other, when the defective filling of the contact plug occurs,inter-layer insulating film 62 cracks at the corner of the outermostboundary. With the groove-shaped pattern (the sub-pattern 90) is furtherprovided outer of the via-hole 66 a, no cracks are made in theinter-layer insulating film 62 at the corner of the inner via-hole 66 a.In the case that the sub-pattern 90 has the pattern as exemplified inFIG. 19, which is free from the defective filling, no cracks are made inthe inter-layer insulating film 62 at the corner of the sub-pattern 90.

The sub-pattern 90 is thus provided, whereby even when the defectivefilling takes place in the contact plug 72 a filled in the via-hole 66a, the cracking of the inter-layer insulating film 62 can be prevented.

As described above, according to the present embodiment, the sub-patternwhich prevents the cracking of the inter-layer insulating film isdisposed adjacent to the groove-shaped via pattern, whereby even whenthe defective filling takes place in the groove-shaped via pattern, thecracking of the inter-layer insulating film can be prevented.

In the present embodiment, the sub-patterns 88, 90 are respectivelyinterrupted at the corner, but as shown in FIG. 20, the sub-pattern 88may be not interrupted at the corner.

In the present embodiment, the sub-patterns are provided, whereby thecracking of the inter-layer insulating film 62 is prevented, but it ispossible that the sub-patterns are provided, and the groove-shapedvia-hole 66 a has the pattern design which is the same as that of thesemiconductor device according to the first to the fourth embodiments.Thus, the generation of the defective filling is suppressed, whereby theeffect of preventing the cracking of the inter-layer insulating film canbe enhanced.

A Sixth Embodiment

The semiconductor device and the method for fabricating the sameaccording to a sixth embodiment of the present invention will beexplained with reference to FIGS. 21 to 23. The same members of thepresent embodiment as those of the semiconductor device and the methodfor fabricating the same according to the first to the fifth embodimentshown in FIGS. 4A to 20 are represented by the same reference numbersnot to repeat or to simplify their explanation.

FIG. 21 is a plan view of the semiconductor device according to thepresent embodiment, which shows the structure thereof. FIGS. 22 and 23are plan views of the semiconductor device according to modifications ofthe present embodiment, which show the structures thereof.

As shown in FIG. 1A, in the device, such as an inductor, a plurality ofgroove-shaped via patterns are arranged on the interconnection 10 forlowering electric resistance etc. Then, in the present embodiment, planedesign examples of groove-shaped via-holes for the case that a pluralityof groove-shaped via patterns are arranged on one interconnection willbe explained.

The semiconductor device and the method for fabricating the sameaccording to the present embodiment is the same as the semiconductordevice and the method for fabricating the same according to the first tothe fourth embodiments except that the plane design of the groove-shapedvia-hole in the groove-shaped via-hole pattern forming region isdifferent from that of the latter.

In the semiconductor device according to the present embodiment, apattern including a plurality of groove-shaped via patterns arrangedadjacent to each other includes as the outermost groove-shaped via-holepattern the pattern of the via-hole 66 a of the semiconductor deviceaccording to the second embodiment shown in FIG. 15.

That is, as shown in FIG. 21, on a pattern of an interconnection 58,patterns of two via-holes 66 b which are bent at 90° at the corner, anda pattern of a via-hole 66 a which is bent twice each at 135° at thecorner.

In the case where groove-shaped contact plugs are disposed adjacent toeach other, when the defective filling of the contact plugs takes place,cracks are made in the inter-layer insulating film 62 at the corner ofthe outermost pattern. However, the via-hole 66 a which is free from thedefective filling is arranged at the outermost boundary, whereby evenwhen the defective filling of the via-hole 66 b takes place, thecracking of the inter-layer insulating film 62 can be prevented.

As described above, in the semiconductor device according to the presentembodiment, having a pattern of a plurality of groove-shaped viapatterns arranged adjacent to each other, the outermost groove-shapedvia pattern is provided by the pattern of the second embodiment, wherebyeven when the defective filling takes place in an inner groove-shapedvia pattern, the cracking of the inter-layer insulating film can beprevented.

In the present embodiment, the outermost groove-shaped via pattern aloneis provided by the pattern of the second embodiment. However, as shownin FIG. 22, all the groove-shaped via patterns may be provided by thepattern of the second embodiment. Thus, the defective filling can besuppressed, and the cracking of the inner-layer insulating film can bemore effectively prevented.

As shown in FIG. 23, in the same way as, e.g., in the modification ofthe second embodiment shown in FIG. 16, the patterns of theinterconnection 58 may be bent as the pattern of the via-hole 66 a.

A Seventh Embodiment

The semiconductor device and the method for fabricating the sameaccording to a seventh embodiment of the present invention will beexplained with reference to FIGS. 24 and 25. The same members of thepresent embodiment as those of the semiconductor device and the methodfor fabricating the same according to the first to the sixth embodimentshown in FIGS. 4A to 23 are represented by the same reference numbersnot to repeat or to simplify their explanation.

FIG. 24 is a plan view of the semiconductor device according to thepresent embodiment, which shows the structure thereof. FIG. 25 is a planview of the semiconductor device according to one modification of thepresent embodiment, which shows the structure thereof.

In the present embodiment, as in the sixth embodiment, plane designexamples of groove-shaped via-holes for the case that a plurality ofgroove-shaped via patterns are arranged on one interconnection will beexplained.

The semiconductor device and the method for fabricating the sameaccording to the present embodiment is the same as the semiconductordevice and the method for fabricating the same according to the first tothe fourth embodiments except that the plane design of the groove-shapedvia-hole in a groove-shaped via pattern forming region is different fromthat of the latter.

In the semiconductor device according to the present embodiment, apattern including a plurality of groove-shaped via patters disposedadjacent to each other includes as the outermost groove-shaped viapattern the pattern of the via-hole 66 a of the semiconductor deviceaccording to the third embodiment shown in FIG. 17.

That is, as shown in FIG. 24, on the pattern of an interconnection 58patterns of two via-holes 66 b which are bent at 90° at the corner, anda pattern of a via-hole 66 a disposed at the outer boundary that the viapattern at the corner is removed.

In the case where the groove-shaped contact plugs are disposed adjacentto each other, when the defective filling of the contact plugs takesplace, cracks are made in the inter-layer insulating film 62 at thecorner of the outermost boundary. However, the via-hole 66 a, which isfree from the defective filling, is arranged at the outermost boundary,whereby even when the defective filling takes place in the via-hole 66b, the cracking of the inter-layer insulating film 62 can be prevented.

As described above, in the semiconductor device according to the presentembodiment, including the pattern of a plurality of groove-shaped viapatterns disposed adjacent to each other, the outermost groove-shapedvia pattern is provided by the pattern of the third embodiment, wherebyeven when the defective filling of an inner groove-shaped via pattern,the cracking of the inter-layer insulating film can be prevented.

In the above-described embodiment, the outermost groove-shaped viapattern alone is provided by the pattern of the third embodiment.However, as shown in FIG. 25, all the groove-shaped via patterns may beprovided by the patterns of the third embodiment. Thus, the generationof the defective filling can be further suppressed, whereby the crackingof the inter-layer insulating film can be effectively prevented.

An Eight Embodiment

The semiconductor device and the method for fabricating the sameaccording to an eighth embodiment of the present invention will beexplained with reference to FIGS. 26, 27A-27B, 28A-28B, 29A-29C, and30A-30C. The same members of the present embodiment as those of thesemiconductor device and the method for fabricating the same accordingto the first to the seventh embodiments shown in FIGS. 4A to 25 arerepresented by the same reference numbers not to repeat or to simplifytheir explanation.

FIG. 26 is a diagrammatic sectional view of the semiconductor deviceaccording to the present embodiment, which shows the structure there of.FIGS. 27A-27B and 28A-28B are sectional views of the semiconductordevice according to the present embodiment in the steps of the methodfor fabricating the same, which show the method. FIG. 29A-29C are viewsexplaining a cause for the generation of the defective filling ofcontact plug. FIGS. 30A-30C are views explaining means in thefabrication steps of preventing the defective filling of the contactplug.

First, the structure of the semiconductor device according to thepresent embodiment will be explained with reference to FIG. 26.

As shown in FIG. 26, the semiconductor device according to the presentembodiment is the same as the semiconductor device according to thefirst embodiment shown in FIG. 5 in the basic sectional structure.Differences of the semiconductor device according to the presentembodiment from the semiconductor device according to the firstembodiment are that etching stopper films 22 a, 36 a, 40 a, 60 a of anSiC film are used in place of the etching stopper films 22, 36, 40, 60of a silicon nitride film, and inter-layer insulating films 24 a, 38 a,42 a of an SiOC film are used in place of the inter-layer insulatingfilms 24, 38, 42 of a silicon oxide film.

The inventor of the present application has confirmed that the crackingis made in the inter-layer insulating film 62 due to the defectivefilling of the contact plug 72 a in the SiOC film/SiC film-basedinter-layer insulating film structure as well as the silicon oxidefilm/silicon nitride film-based inter-layer insulating film structure.The present invention is effective in the SiOC film/SiC film-basedinter-layer insulating film structure.

In the semiconductor device according to the present embodiment, thepatterns of the semiconductor device according to the first to theseventh embodiments are not used as the plane design of the via-hole 66a. As the groove-shaped via pattern, a pattern bent at 90° asexemplified in FIG. 1A may be used. This is for the prevention of thedefective filling of the contact plugs 72 a by a contrivance of thefabrication process which will be described later in the presentembodiment.

Next, the method for fabricating the semiconductor device according tothe present embodiment will be explained with reference to FIGS.27A-27B, 28A-28B, 29A-29C, and 30A-30C.

First, in the same way as, e.g., in the method for fabricating thesemiconductor device according to the first embodiment shown in FIGS. 7Ato 11A, interconnections 34, 58, etc. are formed on a substrate 20. Atthis time, in the present embodiment, the etching stopper films 22 a, 36a, 40 a, 60 a of an SiC film are formed in place of the etching stopperfilms 22, 36, 40, 60 of a silicon nitride film, and the inter-layerinsulating films 24 a, 38 a, 42 a of an SiOC film are formed in place ofthe inter-layer insulating films 24, 38, 42 of a silicon oxide film(FIG. 27A).

Next, in the same way as, e.g., in the method for fabricating thesemiconductor device according to the first embodiment shown in FIG. 11Bto 12A, the etching stopper film 60 a of an SiC film and the inter-layerinsulating film 62 are formed on the inter-layer insulating film 42 awith the interconnections 58 buried in, and then the via-holes 66, 66 aare formed in the inter-layer insulating film 62 and the etching stopperfilm 60 a down to the interconnections 58 (FIG. 27B). In forming thevia-holes, when a design diameter of the via-holes 66 in the innercircuit region is 0.5 μm, and a design width of the via-hole 66 a in thegroove-shaped via pattern forming region is 0.5 μm, as described above,in their finished sizes on a wafer, the diameter of the via-holes 66 isabout 0.5 μm, and the width of the via-hole 66 a is about 0.80 μm atmaximum.

Next, a 50 nm-thick titanium nitride film 68 and a 400 nm-thick tungstenfilm 70 are formed sequentially by, e.g., sputtering and by, e.g., CVD(FIG. 28A).

Next, the tungsten film 70 and the titanium nitride film 68 are planarlyremoved by, e.g., CMP until the inter-layer insulating film 62 isexposed. Thus, the contact plugs 72 which are filled in the via-holes 66and which includes the barrier metal layer 68 a formed of the titaniumnitride film 68, and the tungsten film 70, and the contact plug 72 awhich is filled in the via-hole 66 a and which includes the barriermetal layer 68 a formed of the titanium nitride film 68, and thetungsten film 70 are formed (FIG. 28B).

In the first embodiment, film thickness conditions of the titaniumnitride film 68 and the tungsten film 70 for forming the contact plugs72 are respectively set to 50 nm and to 300 nm so as to sufficientlyfill the via-holes 66. However, such film thickness conditions cancompletely fill the vial holes of a 0.7 μm-maximum width but cannotcompletely fill the via-hole 66 a having a 0.8 μm-maximum width at thecorner (FIG. 29B). Accordingly, when the contact plug 72 a is formedlater by polishing by CMP, the defective filling takes place at thecentral part of the plug (FIGS. 29A and 29C).

Then, in the present embodiment, film thickness conditions for fillingthe via-holes 66 are set in consideration of a maximum width of thevia-hole 66 a. When film thicknesses of the titanium nitride film 68 andthe tungsten film for forming the contact plugs 72 are set to berespectively 50 nm and 400 nm as described above, the via-holes of a 0.9μm-maximum width can be completely filled, and accordingly, the via-hole66 a having an about 0.8 μm-maximum width at the corner can becompletely filled (FIG. 30B). Accordingly, even when the contact plug 72a is formed later by polishing by CMP, the defective filling does nottake place (FIGS. 30A and 30C).

Then, in the same way as, e.g., in the method for fabricating thesemiconductor device according to the first embodiment shown in FIGS.13B to 14, the interconnections 82, a cover film, etc. are formed on theinter-layer insulating film 62 with the contact plugs 72, 72 a buriedin.

As described above, according to the present embodiment, film thicknessconditions for forming the contact plugs are set in consideration of amaximum width of the groove-shaped via pattern, whereby even when adifference takes place in the finished size between the hole-shapedpattern and the groove-shaped pattern, the defective filling of thecontact plug and the interconnection can be prevented. The cracking ofthe inter-layer insulating film due to the defective filling can beprevented.

In the present embodiment, as the inter-layer insulating film structurearound the copper interconnection, the SiOC film/SiC film-basedinsulating film is used, but the silicon oxide film/silicon nitridefilm-based inter-layer insulating film structure may be used as in thesemiconductor device according to the first embodiment.

In the present embodiment, the plane design of the via-hole 66 a is notcontrived, but the via-hole 66 a may use the patterns of thesemiconductor device according to the first to the seventh embodiments.Thus, the generation of the defective filling can be more effectivelyprevented both in the design and the process.

A Ninth Embodiment

The semiconductor device according to a ninth embodiment of the presentinvention will be explained with reference to FIGS. 31 and 32.

FIG. 31 is a diagrammatic sectional view of the semiconductor deviceaccording to the present embodiment, which shows the structure thereof.FIG. 32 is a diagrammatic sectional view of the semiconductor deviceaccording to another example of the present embodiment, which shows thestructure thereof.

In the present embodiment, a specific structure of the semiconductordevice which includes copper interconnections and aluminuminterconnections will be explained. In the above-described first to thethird embodiments, the interconnection layers are three, but thesemiconductor device according to the present embodiment includes threeor more interconnection layers.

The semiconductor device shown in FIG. 31 has the multi-levelinterconnection layer structure including seven copper interconnectionlayers and one aluminum interconnection layer.

A device isolation film 102 for defining device regions is formed on asilicon substrate 100. A MOS transistor including a gate electrode 104and source/drain diffused layers 106 is formed in the device regiondefined by the device isolation film 102.

An inter-layer insulating film 108 of a layer film of a PSG film/asilicon nitride film is formed on the silicon substrate 100 with the MOStransistor formed on. Contact plugs 110 of a layer structure of atungsten film/a titanium nitride film are buried in the inter-layerinsulating film 108.

An inter-layer insulating film 112 of a layer structure of a siliconoxide film/a SiLK (registered trademark) film (or an SOG film) is formedon the inter-layer insulating film 108 with the contact plugs 110 buriedin. Interconnections 114 of a layer structure of a copper film/atantalum film are buried in the inter-layer insulating film 112.

An inter-layer insulating film 116 of a layer film of a silicon oxidefilm/a silicon nitride film is formed on the inter-layer insulating film112 with the interconnections 114 buried in. An inter-layer insulatingfilm 118 of a layer film of a silicon oxide film/a SiLK film (or an SOGfilm) is formed on the inter-layer insulating film 116. Interconnections120 of a layer structure of a copper film/a tantalum film are formed inthe inter-layer insulating films 116, 118 with the via portion buried inthe inter-layer insulating film 116 and the interconnection portionburied in the inter-layer insulating film 118.

An inter-layer insulating film 122 of a layer film of a silicon oxidefilm/a silicon nitride film is formed on the inter-layer insulating film118 with the interconnections 120 buried in. An inter-layer insulatingfilm 124 of a layer film of a silicon oxide film/a SiLK film (or an SOGfilm) is formed on the inter-layer insulating film 122. Interconnections126 of a layer structure of a copper film/a tantalum film are formed inthe inter-layer insulating films 122, 124 with the via portion buried inthe inter-layer insulating film 122 and the interconnection portionburied in the inter-layer insulating film 124.

An inter-layer insulating film 128 of a layer film of a silicon oxidefilm/a silicon nitride film is formed on the inter-layer insulating film124 with the interconnections 126 buried in. An inter-layer insulatingfilm 130 of a layer film of a silicon oxide film/a SiLK film (or an SOGfilm) is formed on the inter-layer insulating film 128. Interconnections132 of a layer structure of a copper film/a tantalum film are formed inthe inter-layer insulating films 128, 130 with the via portion buried inthe inter-layer insulating film 128 and the interconnection portionburied in the inter-layer insulating film 130.

An inter-layer insulating film 134 of a layer film of a silicon oxidefilm/a silicon nitride film is formed on the inter-layer insulating film130 with the interconnections 132 buried in. An inter-layer insulatingfilm 136 of a layer film of a silicon oxide film/a silicon nitride filmis formed on the inter-layer insulating film 134. Interconnections 138of a layer structure of a copper film/a tantalum film are formed in theinter-layer insulating films 134, 136 with the via portion buried in theinter-layer insulating film 134 and the interconnection portion buriedin the inter-layer insulating film 136.

An inter-layer insulating film 140 of a layer film of a silicon oxidefilm/a silicon nitride film is formed on the inter-layer insulating film136 with the interconnections 138 buried in. An inter-layer insulatingfilm 142 of a layer film of a silicon oxide film/a silicon nitride filmis formed on the inter-layer insulating film 140. Interconnections 144of a layer structure of a copper film/a tantalum film are formed in theinter-layer insulating films 140, 142 with the via portion buried in theinter-layer insulating film 140 and the interconnection portion buriedin the inter-layer insulating film 142.

An inter-layer insulating film 146 of a layer film of a silicon oxidefilm/a silicon nitride film is formed on the inter-layer insulating film142 with the interconnections 144 buried in. An inter-layer insulatingfilm 148 of a layer film of a silicon oxide film/a silicon nitride filmis formed on the inter-layer insulating film 146. Interconnections 150of a layer structure of a copper film/a tantalum film are formed in theinter-layer insulating films 146, 148 with the via portion buried in theinter-layer insulating film 146 and the interconnection portion buriedin the inter-layer insulating film 148.

An inter-layer insulating film 152 of a layer film of a silicon oxidefilm/a silicon nitride film is formed on the inter-layer insulating film148 with the interconnections 150 buried in. Contact plugs 154 of alayer structure of a tungsten film/a titanium nitride film are buried inthe inter-layer insulating film 152.

Interconnections 156 of a layer film of a titanium nitride film/analuminum film/a titanium nitride film are formed on the inter-layerinsulating film 152 with the contact plugs 154 buried in.

A cover film 158 of a layer film of a silicon nitride film/a siliconoxide film is formed on the inter-layer insulating film 152 with theinterconnections 156 formed on.

Thus, the semiconductor device having the multi-level interconnectionstructure including seven copper interconnection layers and one aluminuminterconnection layer is formed.

In the semiconductor device shown in FIG. 31, the present invention maybe applicable to the step of forming the contact plugs 154. Accordingly,the defective filling of the contact plugs 154 can be prevented, andresultantly the cracking of the inter-layer insulating film 152 can beprevented. In the case that the defective filling of the copperinterconnections takes place, the present invention may be applicable tothe steps of forming the interconnections 120, 126, 132, 138, 144, 150.In the case that groove-shaped vias are used for the contact plugs 110,the defective filling of the contact plugs 110 can be also prevented.

In the semiconductor device shown in FIG. 32, a multi-levelinterconnection layer structure is formed of ten copper interconnectionlayers and one aluminum interconnection layer.

A device isolation film 202 for defining device regions is formed on asilicon substrate 200. In the device region defined by the deviceisolation film 202, a MOS transistor including a gate electrode 204 andsource/drain diffused layers 206 is formed.

On the silicon substrate 200 with the MOS transistor formed on, aninter-layer insulating film 208 of a layer film of a PSG film/a siliconnitride film is formed. Contact plugs 210 of a layer structure of atungsten film/a titanium nitride film are buried in the inter-layerinsulating film 208.

An inter-layer insulating film 212 of a layer film of an SiC film/a SiLKfilm/an SiC film is formed on the inter-layer insulating film 208 withthe contact plugs 210 buried in. Interconnections 214 of a layerstructure of a copper film/a tantalum film and having the via portionand the interconnection portion are buried in the inter-layer insulatingfilm 212.

An inter-layer insulating film 216 of a layer film of an SiC film/a SiLKfilm/an SiC film is formed on the inter-layer insulating film 212 withthe interconnections 214 buried in. Interconnections 218 of a layerstructure of a copper film/a tantalum film and having the via portionand the interconnection portion are buried in the inter-layer insulatingfilm 216.

An inter-layer insulating film 220 of a layer film of an SiC film/a SiLKfilm/an SiC film is formed on the inter-layer insulating film 216 withthe interconnections 218 buried in. Interconnections 222 of a layerstructure of a copper film/a tantalum film and having the via portionand the interconnection portion are buried in the inter-layer insulatingfilm 220.

An inter-layer insulating film 224 of a layer film of an SiC film/a SiLKfilm/an SiC film is formed on the inter-layer insulating film 220 withthe interconnections 222 buried in. Interconnections 226 of a layerstructure of a copper film/a tantalum film and having the via portionand the interconnection portion are buried in the inter-layer insulatingfilm 224.

An inter-layer insulating film 228 of a layer film of an SiOC film/anSiC film is formed on the inter-layer insulating film 224 with theinterconnections 226 buried in. An inter-layer insulating film 230 of anSiOC film/an SiC film is formed on the inter-layer insulating film 228.Interconnections 232 of a layer structure of a copper film/a tantalumfilm are formed in the inter-layer insulating films 228, 230 with thevia portion buried in the inter-layer insulating film 228 and theinterconnection portion buried in the inter-layer insulating film 230.

An inter-layer insulating film 234 of a layer structure of an SiOCfilm/an SiC film is formed on the inter-layer insulating film 230 withthe interconnections 232 buried in. An inter-layer insulating film 236of a layer structure of an SiOC film/an SiC film is formed on theinter-layer insulating film 234. Interconnections 238 of a layerstructure of a copper film/a tantalum film are formed in the inter-layerinsulating films 234, 236 with the via portion buried in the inter-layerinsulating film 234 and the interconnection portion buried in theinter-layer insulating film 236.

An inter-layer insulating film 240 of a layer film of an SiOC film/anSiC film is formed on the inter-layer insulating film 236 with theinterconnections 238 buried in. An inter-layer insulating film 242 of alayer film of an SiOC film/an SiC film is formed on the inter-layerinsulating film 240. Interconnections 244 of a layer structure of acopper film/a tantalum film are formed in the inter-layer insulatingfilms 240, 242 with the via portion buried in the inter-layer insulatingfilm 240 and the interconnection portion buried in the inter-layerinsulating film 242.

An inter-layer insulating film 246 of a layer film of an SiOC film/anSiC film is formed on the inter-layer insulating film 242 with theinterconnections 244 buried in. An inter-layer insulating film 248 of alayer film of an SiOC film/an SiC film is formed on the inter-layerinsulating film 246. Interconnections 250 of a layer structure of acopper film/tantalum film are formed in the inter-layer insulating films246, 248 with the via portion buried in the inter-layer insulating film246 and the interconnection portion buried in the inter-layer insulatingfilm 248.

An inter-layer insulating film 252 of a layer film of a silicon oxidefilm/an SiC film is formed on the inter-layer insulating film 248 withthe interconnections 250 buried in. An inter-layer insulating film 254of a layer film of a silicon oxide film/an SiC film is formed on theinter-layer insulating film. Interconnection 256 of a layer structure ofa copper film/a tantalum film are formed in the inter-layer insulatingfilms 252, 254 with the via portion buried in the inter-layer insulatingfilm 252 and the interconnection portion buried in the inter-layerinsulating film 254.

An inter-layer insulating film 258 of a layer film of a silicon oxidefilm/an SiC film is formed on the inter-layer insulating film 254 withthe interconnections 256 buried in. An inter-layer insulating film 260of a layer film of a silicon oxide film/an SiC film is formed on theinter-layer insulating film 258. Interconnections 262 of a layerstructure of a copper film/a tantalum film are formed in the inter-layerinsulating films 258, 260 with the via portion buried in the inter-layerinsulating film 258 and the interconnection portion buried in theinter-layer insulating film 260.

An inter-layer insulating film 264 of a layer film of a silicon oxidefilm/an SiC film is formed on the inter-layer insulating film 260 withthe interconnections 262 buried in. Contact plugs 266 of a layerstructure of a tungsten film/a titanium nitride film are buried in theinter-layer insulating film 264.

Interconnections 268 of a layer film of a titanium nitride film/analuminum film/titanium nitride film is formed on the inter-layerinsulating film 264 with the contact plugs 266 buried in.

A cover film 270 of a layer film of a silicon nitride film/a siliconoxide film is formed on the inter-layer insulating film with theinterconnection 268 formed on.

Thus, the semiconductor device including the multi-level interconnectionlayer structure including ten copper interconnection layers and onealuminum interconnection layer is formed.

In the semiconductor device shown in FIG. 32, the present invention maybe applicable to the step of forming the contact plugs 266. Accordingly,the defective filling of the contact plugs 266 can be prevented, andaccordingly the cracking of the inter-layer insulating film 264 can beprevented. In the case the copper interconnection has the defectivefilling, the present invention may be applicable to the step of formingthe interconnections, 214, 218, 222, 226, 232, 238, 244, 250, 256. Inthe case that the contact plugs 210 are buried in groove-shaped vias,the defective filling of the contact plugs 210 can be also prevented.

Modified Embodiments

The present invention is not limited to the above-described embodimentsand can cover other various modifications.

For example, in the above-described embodiments, structures thegroove-shaped via patterns are used in are inductors. However,structures the groove-shaped via patterns are used in are not limited toinductors.

In forming a plurality of semiconductor devices on a wafer, as shown inFIG. 33A, each semiconductor circuit region is surrounded by a guardring 92 for protecting the device from water, etc. from theenvironments. As shown in FIG. 33B, this guard ring 92 is formed byusing the groove-shaped via pattern 94. As shown in FIG. 34A, the guardring 92 is provided around a fuse pattern 96 of a redundant circuit. Asshown in 34B, this guard ring 92 is also formed by using thegroove-shaped via pattern 94. Accordingly, the structure according tothe present invention is used in the corners of these guard rings,whereby the cracking of the inter-layer insulating films of the guardrings at the corners can be prevented, whereby the semiconductor devicecan have improved water resistance.

In the above-described embodiments, the uppermost interconnection layeralone is formed of aluminum interconnection layer, but two or morealuminum interconnection layers may be used. The present invention iswidely applicable to semiconductor devices having the structure thattungsten plugs are used as a connection between a copper interconnectionlayer and an aluminum interconnection layer. The interconnection layerstructure and the insulating film structure applicable to the presentinvention are not limited to the structures described in theabove-described embodiments.

For the prevention of the defective filling, the present invention maybe applicable to the contact plugs on a substrate, and disadvantages informing upper interconnection layers can be prevented.

In the above-described sixth and seventh embodiments, the patternexamples used in a plurality of groove-shaped via patterns arrangedadjacent to each other are explained by means of the patterns of thesecond embodiment and the third embodiment. However, the pattern of thefirst embodiment or the pattern of the fourth embodiment may be used informing a plurality of groove-shaped via patterns. In arranging aplurality of groove-shaped via patterns, the sub-patterns of the fifthembodiment may be provided at the outer boundary.

What is claimed is:
 1. A semiconductor device comprising: a substrate; afirst insulating film formed on the substrate; a second insulating filmformed above the first insulating film; a third insulating film formedabove the second insulating film; an aluminum interconnection formedabove the third insulating film; a first guard ring including a firstgroove-shaped via-hole formed in the first insulating film, a firstconductor buried in the first groove-shaped via-hole and connected tothe substrate, a second groove-shaped via-hole formed in the secondinsulating film, a first buried copper buried in the secondgroove-shaped via-hole above the first conductor and electricallyconnected to the first conductor, a third groove-shaped via-hole formedin the third insulating film, and a second buried copper buried in thethird groove-shaped via-hole above the first buried copper andelectrically connected to the first buried copper; and a second guardring including a fourth groove-shaped via-hole formed in the firstinsulating film, a second conductor buried in the fourth groove-shapedvia-hole and connected to the substrate, a fifth groove-shaped via-holeformed in the second insulating film, a third buried copper buried inthe fifth groove-shaped via-hole above the second conductor andelectrically connected to the second conductor, a sixth groove-shapedvia-hole formed in the third insulating film, and a fourth buried copperburied in the sixth groove-shaped via-hole above the third buried copperand electrically connected to the third buried copper, wherein thesecond guard ring is surrounded by the first guard ring in a plan view,the first guard ring is connected to the aluminum interconnection, andeach of the first groove-shaped via-hole, the second groove-shapedvia-hole, the third groove-shaped via-hole, the fourth groove-shapedvia-hole, the fifth groove-shaped via-hole and the sixth groove-shapedvia-hole includes a pattern bent twice each time at an inner angle oflarger than 90° at each of four corners of the semiconductor device in aplan view.
 2. The semiconductor device according to claim 1, wherein thefirst insulating film includes a silicon oxycarbide film.
 3. Thesemiconductor device according to claim 1, wherein the first insulatingfilm includes a PSG film.
 4. The semiconductor device according to claim1, wherein the second insulating film includes a silicon oxycarbidefilm.
 5. The semiconductor device according to claim 1, wherein thefirst conductor and the second conductor include a tungsten film and atitanium nitride film.
 6. The semiconductor device according to claim 1,wherein the first buried copper, the second buried copper, the thirdburied copper and the fourth buried copper include a copper film and atantalum film.
 7. The semiconductor device according to claim 1, whereinthe third insulating film includes a silicon oxycarbide film.
 8. Asemiconductor device comprising: a substrate; a first guard ringincluding a first conductor buried in a first groove-shaped via-hole ina first insulating film and connected to the substrate, a first buriedcopper buried in a second groove-shaped via-hole in a second insulatingfilm above the first conductor and electrically connected to the firstconductor, and a second buried copper buried in a third groove-shapedvia-hole in a third insulating film above the first buried copper andelectrically connected to the first buried copper; and a second guardring including; a second conductor buried in a fourth groove-shapedvia-hole in the first insulating film and connected to the substrate, athird buried copper buried in a fifth groove-shaped via-hole in thesecond insulating film above the second conductor and electricallyconnected to the second conductor, and a fourth buried copper buried ina sixth groove-shaped via-hole in the third insulating film above thethird buried copper and electrically connected to the third buriedcopper, wherein the second guard ring is surrounded by the first guardring in a plan view, the first guard ring is connected to an aluminuminterconnection, and each of the first groove-shaped via-hole, thesecond groove-shaped via-hole, the third groove-shaped via-hole, thefourth groove-shaped via-hole, the fifth groove-shaped via-hole and thesixth groove-shaped via-hole includes a pattern bent twice each time atan inner angle of larger than 90° at each of four corners of the devicein a plan view.
 9. The semiconductor device according to claim 8,wherein the first insulating film includes a silicon oxycarbide film.10. The semiconductor device according to claim 8, wherein the firstinsulating film includes a PSG film.
 11. The semiconductor deviceaccording to claim 8, wherein the second insulating film includes asilicon oxycarbide film.
 12. The semiconductor device according to claim8, wherein the first conductor and the second conductor include atungsten film and a titanium nitride film.
 13. The semiconductor deviceaccording to claim 8, wherein the first buried copper, the second buriedcopper, the third buried copper and the fourth buried copper include acopper film and a tantalum film.
 14. The semiconductor device accordingto claim 8, wherein the third insulating film includes a siliconoxycarbide film.